Path: utzoo!utgpu!watmath!att!cbnewsc!psfales
From: psfales@cbnewsc.ATT.COM (Peter Fales)
Newsgroups: unix-pc.general
Subject: Re: .5 + .5 + .5 + 1.5 = 2.0 ?
Message-ID: <4162@cbnewsc.ATT.COM>
Date: 27 Oct 89 21:55:56 GMT
References: <4224@itivax.iti.org> <10383@cbnews.ATT.COM>
Organization: AT&T Bell Laboratories
Lines: 27

In article <10383@cbnews.ATT.COM>, mvadh@cbnews.ATT.COM (andrew.d.hay) writes:
> In article <4224@itivax.iti.org> scs@itivax.iti.org (Steve Simmons) writes:
> "
> "I recently added a combo card with 1.5MB to lokkur, which already
> "had .5 on the motherboard and 2 .5MB expansion cards.  Instead of
> "getting 3.0MB, there's only 2.0.

I was waiting for someone who knows a little bit more about this to
say something, but since I haven't heard anything, I will take a stab...

As I understand it, the UNIX-PC supports 2MB of expansion memory.  Each
slot has .5 MB dedicated to it, and when you plug in a 512K board, it
uses the connector to determine which slot it is plugged into, and therefore
which address range to use.  If you have a 1.5MB board, it ignores the
slot position, and just uses all three .5MB banks.

John Milton has posted instructions for modifying a 512K board to look
as if it is plugged into the phantom "fourth slot" and used this range
which is normally used only by the 2MB expansion card.  If you use
this fix, you could have .5MB on the mother board, a 1.5MB combo, and 
a .5MB expansion card, for a total of 2.5MB.

-- 
Peter Fales			AT&T, Room 5B-420
				2000 N. Naperville Rd.
UUCP:	...att!peter.fales	Naperville, IL 60566
Domain: peter.fales@att.com	work:	(312) 979-8031